1. Field of the Invention
The present invention relates to an image forming device such as a copy machine, a printer and a facsimile machine, and more particularly to an image forming device in which a developing unit is inserted removably.
2. Description of the Related Art
Various types of image forming devices have been developed from a technical aspect to form an image with a high resolution and an aspect of a business use or a domestic use. As a developing unit which can be inserted into various types of image forming devices, various types of developing units have been developed. Therefore, for an image forming device of a prescribed type, a developing unit compliant with the image forming device of the prescribed type is necessary to be inserted. When a noncompliant developing unit is inserted, there are cases in which the image forming device breaks down. Therefore, it is necessary to ensure compatibility between the image forming device and the developing unit to be inserted.
For example, in a first conventional device, a fuse and a resistance are mounted on a developing cartridge. In the first conventional device, when the cartridge is inserted into the image forming device frame, by the continuity to the fuse, an initial continuity is detected and the fuse is blown out. In addition, a resistance value is checked and a determination is made as to whether the cartridge complies with the device frame.
In a second conventional device, a determination is made as to whether a developing unit is a new one or an old one according to whether a fuse is connected or blown out.
In a third conventional device, an antenna is provided on a cartridge for detecting a remaining amount of toner in a developing unit. A fuse is connected between the antenna and ground. When the antenna detects the remaining amount of toner, if the detection result is the same voltage as ground, a determination is made that the cartridge is new.
In the above-described first, second and third conventional devices, the fuse is attached to the developing unit. When the developing unit is inserted into the device frame, the fuse is blown out. When a used developing unit is inserted into the device frame, since the fuse is already blown out, the continuity is lost. Therefore, it can be recognized at the device frame that the inserted developing unit is a used developing unit. Such a structure enables an accurate detection of old and new developing units by a simple structure. However, the structure is unsuitable for detections other than the detection of old and new developing units.
Therefore, there is a demand for an image forming device which can accurately detect the type of the developing unit by a simple structure.
Moreover, it is not sufficient just to ensure the compatibility of the image forming device and the developing unit as described above. It is preferable to enable an operator to recognize the compatibility. Fourth and fifth conventional devices are proposed in consideration to such a demand.
In the fourth conventional device, a developing unit and an image forming device are provided with an engaging member and an engaged member to be engaged with one another when the developing unit is inserted into the image forming device frame. Therefore, when a developing unit of a different type is inserted into the image forming device, the engaging member and the engaged member are not engaged with one another.
In the fifth conventional device, a developing unit is provided with a connector having contacts of different connections according to a designated image forming device. An image forming device includes an electrical signal relay unit. When the electrical signal replay unit engages with the connector, an electrical signal of a plurality of contacts is read. Then, a determination is made as to whether the inserted developing unit is for that image forming device.
In the above-described fourth and fifth conventional devices, the identification of the developing unit is carried out only once. Therefore, when the number of different types of developing units increases, the image forming device cannot handle these increases. That is, when there exists various types of image forming devices, to acquire identification information of an image forming device from the developing unit by carrying out the identification of the developing unit only once, the developing unit is required to be provided with an identifier indicating many pieces of identification information. In addition, the image forming device is required to carry out processes for reading many pieces of identification information. Therefore, the cost for the developing unit and the image forming device increases.
Thus, there is a demand for a developing unit which can ensure compatibility for various types of developing units and which the compatibility can be recognized easily by the operator, and a method for distinguishing the type of the developing unit.
In the fourth conventional device, a mechanical device and an electrical device are used for ensuring the compatibility. However, when the number of different types of image forming devices increases, the number of patterns relating to the compatibility also increases. Therefore, it is difficult for the fourth conventional device to sufficiently comply with such a large number of patterns.
Thus, there is a demand for an image forming device which can flexibly comply with an increase in the number of different types of image forming devices.